Cyclic Citrullinated Peptide Antibody
Also known as:CCP Antibody; Citrulline Antibody; Anti-citrulline Antibody; Anti-cyclic Citrullinated Peptide; Anti-CCP; ACPA
Formal name:Cyclic Citrullinated Peptide Antibody
Related tests:Rheumatoid Factor, ESR, C-Reactive Protein, ANA, Synovial Fluid Analysis
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Why Get Tested?
To help diagnose rheumatoid arthritis (RA) and differentiate it from other types of arthritis; to help evaluate the prognosis of a person with RA
When to Get Tested?
When a health practitioner suspects RA in someone who has joint inflammation with symptoms that suggest but do not yet meet the criteria of RA
A blood sample drawn from a vein in your arm
Test Preparation Needed?
How is it used?
A cyclic citrullinated peptide (CCP) antibody test may be ordered along with or following a rheumatoid factor (RF) test to help diagnose rheumatoid arthritis (RA) and to assess the severity and probable course of the disease (prognosis). Inflammatory markers may also be measured at this time, such as ESR and C-reactive protein (CRP).
Cyclic citrullinated peptide antibodies are autoantibodies produced by the immune system that are directed against cyclic citrullinated peptides (CCP). (See the "What is being tested?" section for more.)
CCP antibody testing may also be ordered to help evaluate the likely development of RA in people with undifferentiated arthritis - those whose symptoms suggest but do not yet meet the American College of Rheumatology (ACR) criteria for RA. According to ACR, approximately 95% of those with a positive CCP antibody will meet the criteria of RA in the future. Early detection of RA is essential for guiding treatment decisions.
When is it ordered?
A CCP antibody test is primarily ordered along with an RF test when someone has signs and symptoms that may be due to previously undiagnosed inflammatory arthritis or has been diagnosed with undifferentiated arthritis. It may be ordered as a follow-up test to a negative RF test when clinical signs and symptoms lead a health practitioner to suspect RA. RA usually affects multiple joints symmetrically. Signs and symptoms may include:
- Painful, warm, swollen joints of the hands and wrists most commonly
- Pain sometimes affecting elbows, neck, shoulders, hips, knees, and/or feet
- Stiffness of affected joints in the morning that improves during the course of the day
- Development of nodules under the skin, especially at the elbows
- A general feeling of being unwell (malaise)
What does the test result mean?
When people with signs and symptoms of arthritis are positive for both CCP antibody and RF, it is very likely that they have RA and it is likely that they may develop a more rapidly progressive and severe form of the disease. When people are positive for CCP antibody but not RF, or have low levels of both, and have clinical signs that suggest RA, then it is likely that they have early RA or that they will develop RA in the future.
When individuals are negative for CCP antibody but have a positive RF, then the clinical signs and symptoms are more vital in determining whether they have RA or some other inflammatory condition. When someone is negative for both CCP antibody and RF, then it is less likely that the person has RA. It must be emphasized, however, that RA is a clinical diagnosis and may be made in the absence of positive tests for autoantibodies.
Is there anything else I should know?
The CCP antibody test is relatively new. It is becoming more widely used but is still less frequently ordered than the RF test.
CCP antibodies are rarely found in other autoimmune conditions, such as lupus, Graves disease and Sjogren syndrome, and may be detected in infections such as tuberculosis.
What is being tested?
Cyclic citrullinated peptide antibodies are autoantibodies produced by the immune system that are directed against cyclic citrullinated peptides (CCP). This test detects and measures anti-CCP antibodies in the blood.
Citrulline is naturally produced in the body as part of the metabolism of the amino acid arginine. However, in joints with rheumatoid arthritis (RA), this conversion may occur at a higher rate. Citrulline changes the protein structure and can trigger an immune response, producing autoantibodies against joint proteins. The CCP antibody test helps to diagnose RA and can be useful in identifying people with a more rapidly erosive form of the disease.
RA is a chronic, systemic autoimmune disease that causes inflammation, pain, stiffness, and destructive changes in the hands, feet, and other joints throughout the body. It can affect anyone at any age, but it usually develops between the ages of 40 and 60, and about 75% of those affected are women. The course of RA and its prognosis are variable. It may develop and progress slowly or rapidly. It may go into remission in some people and, in a few, it may go away. Left untreated, RA can shorten a person's lifespan and can, within a few years, leave many of those affected too disabled to work.
There are a variety of treatments available to minimize the complications of RA, but they depend on making an accurate diagnosis and on beginning treatment before the development of significant joint damage. Rheumatoid factor (RF) has been the primary blood test used to detect RA and distinguish it from other types of arthritis and other inflammatory processes. However, the sensitivity and specificity of RF are not ideal; it can be negative in people who have clinical signs of RA and positive in people who do not. Studies have shown that the CCP antibody test has a sensitivity and specificity that is equal to or better than RF and is more likely to be positive with early RA.
The 2010 Rheumatoid Arthritis Classification Criteria from the American College of Rheumatology (ACR) includes CCP antibody testing, along with RF, as part of its criteria for diagnosing rheumatoid arthritis. According to the ACR, CCP antibodies may be detected in about 50-60% of people with early RA, as early as 3-6 months after the beginning of symptoms. Early detection and diagnosis of RA allows healthcare providers to begin aggressive treatment of the condition, minimizing the associated complications and tissue damage.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
- Should everyone be tested for CCP antibody?
No. CCP antibody is not recommended as a screening test. Like RF, it is best used to evaluate individuals whose clinical signs suggest RA or who have already been diagnosed with undifferentiated arthritis.
- Can I be tested for CCP antibody in my doctor's office?
Anti-CCP testing is widely available and may be tested for by your physician. This test may not be available in all laboratories but can be routinely sent to a reference laboratory.
- Will my CCP antibody ever go away?
Like other autoantibodies, once developed by the body's immune system, levels of CCP may fluctuate over time but will not go away. CCP antibody levels may decrease with treatment.
- What other tests might my doctor order in evaluating me for RA?
Your healthcare provider may choose to order an ESR and/or CRP, tests that detect inflammation. The health practitioner may also order a complete blood count (CBC) to check for a high white blood cell count, another sign of inflammation, and to check for anemia, a condition common in people with RA. For added information, an analysis of joint fluid (synovial fluid) may be performed. In addition, your healthcare provider may also order antinuclear antibody (ANA) testing. A negative ANA helps exclude lupus and other systemic rheumatic diseases; the ANA may be positive in up to one-third of patients with RA.
© 2017 American Association for Clinical Chemistry, republished from Lab Tests Online.*
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